Contemporary helicopters often exhibit a low efficiency of the drive system. In addition, the drive is often very loud. The main gear units have a fixed transmission ratio, are often relatively expensive, and have a limited torque capacity.
The drive train in known helicopters comprises an internal combustion engine and a mechanical main gear unit. Turbine shaft drives or reciprocating piston engines are frequently used.
DE 10 2008 028 866 A1 as well as WO 2009/153236 A2 describe a helicopter with a swashplate actuator.